Routers are commonly used at interfaces between local area networks (LANs) and wide area networks (WANs). For example, routers may be used to multiplex between “N” number of LAN interfaces and “M” number of WAN interfaces. Sometimes, the WAN interfaces may be grouped into bundles through the use of a multi-link protocol, such as the multi-link point-to-point protocol (MLPPP). Such MLPPP bundles may be associated with a specific LAN interface by either a static or policy-based routing implementation.
FIG. 1 illustrates a situation where a router resource 10 is used as an interface between N LAN ports 12 and M WAN links 14. The WAN links 14 are grouped into various bundles 16 of, for example, 3 4 or 5 WAN links.
Often, the individual LAN ports 12 are leased by separate customers, each with a variable amount of traffic to be switched through router resource 10. For example, in the situation illustrated in FIG. 1, there may be eight 10BaseT LAN ports 12, each associated with a separate customer. These eight LAN ports may be associated through router resource 10 with 24 T1 WAN links 14, grouped into various bundles 16 assigned to the LAN ports 12. The bundling of WAN links 14 provides a variable amount of bandwidth to the customers connecting through the LAN ports 12.
Usually the individual customers have lease rates for router resource 10 associated with the number of WAN ports 14 assigned to their respective LAN interfaces. The number of WAN ports so bundled is generally determined by the amount of traffic the customer will have to transmit through router resource 10. However, owing to the nature in which router resource 10 operates, if one customer (or a few customers) over drives its (their) respective LAN interface(s) beyond capacity, router resource 10 can become overloaded and cause significant loss of performance for the other customers. That is, over driving just one of the LAN ports 12 may cause traffic on other LAN ports 12 to be dropped. What is needed, therefore, is a means of preventing traffic on one, or few, LAN ports of router resource from dramatically affecting performance on other LAN ports thereof.